Michel and Naatje had more than one child

According to http://home.hccnet.nl/r.bobbe/danser/danser.htm#BM1230
and the fact that I grew up with Michel and Naatje's great granddaughter I know that they had 4 children before Naatje's death. 2 daughters were murdered in the Holocaust while the other 2 eventually made their way to Pittsburgh, Pennsylvania, USA